- Albert Square - heretical lunatic and mathematician
- Professor Quatremass - professional sceptic - suggested by sharikkamur
- Ellery Quinn - the great detective
- Rhombus - an immortal who owes his power to a tiny extension into the third dimension
- Lois Line - unusually intelligent female reporter for the Logopolis Daily Plane, in search of a story that will make her name. This was inspired by kip_w's suggestion of Perry Llelogram.
Just need one more, preferably some sort of mathematician with at least 5-6 sides. Any suggestions?
LATER: speakr2customrs has suggested Septimus Prime, which I think will do nicely. Also got some nice suggestions which will do for NPCs and/or future adventures. Thanks, everyone!